Electric furnace



z A. M. ERICHSEN.

' ELECTRIC FURNACE. AP' ucmoN man NOV. 28, 1919.

Patented Feb. 1, 1921c 2 SHEETS-SHEET I- 7 i i fil/l/l/ g A. M. ERECHSEN.

ELECTRIC FURNACE.

APPLICATION FILED NOV. 28. 1919.

Patented Feb. 1, 1921..

2 SHEETS-SHEET 2. #1-

UNITED STATES PATENT OFFICE.

ABRAHAM MARTHIN'IUS sarcasm, or roitseaunn, NORWAY.

ELECTRIC FURNACE.

Specification of Letters Patent.

Application filed November 28, 1919. Serial No. 341.239.

" To all whom it may concern exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters or figures of reference markedthereon, which form a part of this specification.

cally heated furnaces, especially metal smelting furnaces, in which the prlnciple of The present invention relates to electriradiation, known from various kinds of reaction furnaces, is utilized, and in which electrical resistance bodies are arranged for that purpose above the charge of the furnace. According to the invention the resistance bars are arranged similar to grates in one or more rows above the charge and beside each other so as to be freely movable, whereby a uniform intensive heating'is obtained throughout the whole extent of the charge. In order to prevent tne metal vapors and other gases, that will be formed in the furnace specially upon superheating of the alloy contained in the furnace, for instance brass, from penetrating and condensing in the openings in the furnace walls, provided for the free passage of the resistance bars, whereby the free movability of the resistance bars might be prevented and their durability reduced, the space above the charge is kept under a slightly reduced pressure during the smelting process. The vapors formed will then lose their tendency of penetrating into and out from the said openings, and in fact the external airbecause of the slightly reduced pressure inside the furnacewili tend to penetrate through the bar openings and into the furnace so as to keep the said openings free.

' In the accompanying drawing several embodiments of the invention are shown.

Figure 1 shows'the electrical smelting furnace in vertical longitudinal section.

Fig. 2 is a vertical cross section of the same.

Figs. 3-5 show three other embodiments of the furnace in section.

According to all of the embodiments shown the furnace consists of a box 2" of iron or the like, lined with refractory mater1al 1 such as chamotte and pivoted upon trunnions 3, a.

Accordin rests in uprights 5, 6, and may be tilted by means of the worm wheel 7. 8 is the charging opening, which may also be used for emptying the furnace after the smelting is finished. At a distance above the bath ll a large number of parallel electric resistance bars 10 are arranged in a row spaced a short distance apart, thus forming a flat longish resistance grate, which by its radiation ef-- opening 8 after finishing the smelting, but

during the smelting process the distance between tnc heating bar grate 10 and the metal bath 11 may be varied, whereby part of the molten mass may be subjected to more or less intensive heat at will (see the position indicated by dotted lines in Fig. 1).

According to Fig. 3 of the drawing a double-row grate 10 of heating bars is placed at some distance above the charge 11, said grate being in its middle interrupted by the charging hopper 13. This arrangement of the nopper permits the charge to be thoroughly preheated by the heating bar grate arranged on both'sides of the hopper 13.

To prevent the metal vapors or other gases, which are formedduring the smelting process, from penetrating into the openings 16 in the furnace walls, through which the resistance bars extend to the outside of the furnace, whereby the free longitudinal movement of the heating bars 10 would be interfered with, because the said vapors would condense in the openings 16, a slightly reduced pressure is maintained inside of the furnace above the charge 11. According to Fig. 3 a vent opening 14 is provided for this purpose in the furnace cover, said opening causing a gentle flow of metal vapors o1 Patented Feb. 1, 1921..

to Figs. 1 and 2 the furnace other gases out through the charging hopper 13. The openings 16 in the furnace walls thus will be kept free from the said vapors.

giiccording to Fig. 4: a double-row resista co 10 is arranged in similar manner a distance above the metal bath 11. The furnace is here also provided with a special preheating compartment 12 arranged above the smelting compartment proper and heated from below by the double-row heating bar grate 10. The vapors formed above the smelting bath may in this construction escape either through the connecting charging hopper 1? or through lateral openings 15 into the preheating compartment 12 and then through the vent opening let in the cover out in the open air.

In the furnace according to Fig. 5 the heating bars 10 are placed at right angles to the tilting axis. The charging hopper 13 is disposed laterally, but in this arrangement the preheating of the chargeis not as good as in the constructions shown in Figs. 3 and 1, in which the hoppers 13 and 17 respectively, that lead the charge to the furnace project through the central part of the heating grate, whereby the charge within the hoppers is heated from both sides by the radiation of the heating grate. The vent or outflow of the escaping vapors takes place either through the laterally provided charging hopper 13 and through the upper opening 1 1 or through a special vent pipe 18, which leads to the furnace above the heating bar grate. According to Fig. 5 the furnace is placed on wheels 19 and may'thus be transported. The wheels 19 turn 011 the tilting axis i of the furnace.

The vent openings in all of the furnace constructions may preferably be adjusted, in order to permit the control of the reduced pressure within the furnace, and to be able to make the vent openings very small during particularly the latter part of the smelting process. The desired adjustment of the vent openings may be obtained in any wellknown'way-for instance by means of valve slides, dampers, etc.

The resistance bars may be round, polygonal or of any other section. Instead of be ing parallel, they may also be arranged like a grate or in other ways as for instance radially or concentrically. The resistance bars may also be replaced by plates arranged beside each other.

The resistance bars consist of conductors of second class, preferably of carbids such as-silicium carbid, and are able to endure constantly temperatures of 1400-1600 centigrade. The furnace therefore is preferably employed for the smelting of metals fusible with diiiiculty, the smelting points of which are below the said temperatures, for instance copper, nickel, aluminium, iron, etc., as well the alloys of these metals,

particularly brass alloys. The furnace, however, may also be employed for the smelting of other materials and for other purposes, for instance for distilling purposes.

Claims.

1. .An electrical furnace having one or more grate like resistors above the charge and means to permit the furnace to be tilted to vary the distance between the charge and resistors.

2. Furnace according to claim 1, characterized by the fact, that the furnace space above the charge is subjected to a slightly reduced pressure during the process in order to prevent clogging by condensed vapors of the openings in the furnace walls, through which the resistance bars extend to the outside, and to thus maintain the free movability of the resistance bars.

3. Furnace according to claim 2, characterized by the fact, that above the heating grate vent openings are provided, which cause a slight draft (like a chimney) from the furnace interior above the charge.

4. Furnace according to claim 3, characterized by the fact, that the vent openings are adjustable in order to control the reduced pressure within the furnace.

5. Furnace according to claim 1, characterized by the fact, that the single-row or double-row heating ba-r grate is interrupted by-the projecting charging hopper, whereby a preheating of the charge contained in the hopper is obtained by the heat radiation from both sides from the heating bar grate.

6. In an electrical furnace one or. more grate like resistors arranged above the hearth, a charging chamber arranged to extend between the resistors and below their level but terminating above said hearth and means for tilting said furnace to regulate the distance of the molten bath from the resistors.

7. In an electrical furnace, one or more rato like resistors arranged within the furnace chamber out of contact with the hearth thereof. a charge preheating chamber extending over the resistors and having a discharge hopper extending between resistors and means to conduct gases from the furnace chamber into the pro-heating chamber.

8. In an electrical furnace, one or more grate like resistors arranged within the fur nace chamber out of contact with the hearth thereof, a charge preheating chamber extending over the resistors and having discharge hopper extending between resistors, means to conduct gases from the furnace chamber into the ,pre-heating chamber, means to permit the tilting of the furnace and means to draft the furnace chamber through the preheating chamber, said resistors resting in openings in the sides of said furnace whereby outside air is drafted through said openings into the furnace chamber ate-i them e in'ise "the extending between resistors and mm their chamber. level into the furnace chamber and. mews to 9. In an electrical revefbemiery furnace tilt the fumaee.

having a hearth, a preheating ehemlaer In testimony that claim the feregeing 5 tending over ehe hearth, 0116 01" more superas my invention, 1 have signed my name in '15 posed rows or resistors fanning like presence of two subscribing Witnesses. resister elements arranged abeve the Le -Till ABE-515mm MARTHWUF? E Q E be the preheating chamber, passages Witnesses: connecting the fa nace chamber lliAelyrUs BUGGE l0 heating chamber, and a discharge 1 @LGA 

